I used a product called " Quietboat " from a marine supplier. It is waterbased and paints on like a thick latex. I got a good spec coverage with three coats ( drys in a few hours and you can see it dry as it turns a lighter gray) It does the job and is cost effective. I used less than a gallon for the inside of a panel truck. There is a demo using symbols on their web site and when I picked up the product at Harrisjet in Woodenville WA they had a set of coated and uncoated symbols there. It works just as advertised. on the panel sides I used a butyl moisture barrier(Homedepot). It didn't stick all that well until I used a heat gun and rubber stitching tool. It is not the design intention to stick it to other than horizontal surfaces but I think it may work longterm. I did this before I found the Quietboat and if I were to do it again I would use the butyl paint on the whole thing--floorboards firewall inside dooors everywhere. Note: I prepared and painted prior to applying any sound dampening. I used aluminum sound insulation(Homedepot) and doorskin panels(lumberyard) for the sides and a synthetic 1/2 " auto insulation (auto uppolstery shop) glued up with 3M 77 spray contact cement and water proof cardboard for the headliner. I found doublebacked carpet tape helpful for holding the panels in place while I screwed the support pieces to the overhead cross braces.. get some help... I made my strips from door skin but aluminum might be better because of the severe arc at the sides. I still haven't figured out how to do the right and left rear corners due to the odd curved shape. In the rearmost center bay I put a box for a dome light and a couple of rear speakers. It sounds good in the old truck these days. It was a hell of a job and I'm glad it is over
Tom
